Ring hammers

ABSTRACT

A ring hammer for use on the rotor of a material reducing machine and having a plurality of generally radial teeth which are interconnected by integrally formed fillets. The fillets, axially narrower than the teeth, act to prevent scrap material from lodging between the teeth to thus avoid any distending of the ring hammers. Furthermore, the fillets have cutting edges which extend continuously between adjacent teeth and act along with the teeth to shred material.

United States Patent Inventor Sven B. Strom St. Louis, Mo. Appl. No. 772,505 Filed Nov. 1, 1968 Patented May 25, 197i Assignee American Pulverizer Company St. Louis, Mo.

RING HAMMERS 15 Claims, 4 Drawing Figs.

US. Cl 241/193 Int. Cl ..B02c 13/28, B02c 13/04 Field of Search 241/ 193, 196

[56] References Cited UNITED STATES PATENTS 2,207,455 7/1940 Clement 24l/l96X FOREIGN PATENTS 273,465 4/1930 ltaly 241/196 Primary ExaminerDonald G. Kelly Attorney-Gravely, Lieder and Woodruff ABSTRACT: A ring hammer for use on the rotor of a material reducing machine and having a plurality of generally radial teeth which are interconnected by integrally formed fillets. The fillets, axially narrower than the teeth, act to prevent scrap material from lodging between the teeth to thus avoid any distending of the ring hammers. Furthermore, the fillets have cutting edges which extend continuously between adjacent teeth and act along with the teeth to shred material.

Patented May 25, 1971 FIG.3

. 5 m M m MM w B FIG.4

KING IIAMMERS This invention relates in general to machines for reducing material and more particularly to ring-type hammers for such machines.

Pulverizing, crushing and shredding machines having rotors provided with loosely fitted ring hammers are commonplace and are desirable in many reduction operations, inasmuch as the ring hammers tend to rotate with respect to the rotor itself upon impacting with the material to be reduced. As a result the wear is distributed evenly over a number of different cutting edges on each of the rings as they sweep past the grate bars, whereas on swing hammers and fixed hammers the wear is confined primarily to one cutting edge. This accounts for the fact that ring hammers are more durable than swing hammers or fixed hammers. Moreover, ring hammers tend to withdraw into the rotor upon encountering oversized or extremely tough material, and this avoids many failures which would otherwise occur if the hammers were mounted differently.

Generally speaking, the ring-type hammers currently available on the market either assume the configuration of a simple annulus or an annulus having outwardly projecting teeth. Both configurations are illustrated in US. Pat. Nos. 1,424,922 and 1,862,889. The latter configuration exposes more cutting edges to the material and is therefore more suitable for shredding operations.

By reason of high transportation costs, it is desirable in metal recovery operations to reduce metal scrap to small shredded bits so that it consolidates and more efficiently utilizes the space in rail cars and other conveyances consigned to return it to the smelter. To this end tumings, stamping ends, small castings and extrusions, and the like are introduced into shredders and these shredders are generally provided with ring hammers of the toothed variety. While ring hammers in such applications effectively and efficiently shred the metal scrap, the rings in time tend to elongate into a somewhat elliptical configuration. When this occurs the tendency of the rings to rotate upon engagement with the material is greatly retarded, causing the rings to wear unevenly and disturb the balance of both the rings and the rotor. Moreover, the ring distortion on occasion is of such a magnitude that the peripheral surfaces of some of the rings contact the grate bars, thereby unnecessarily wearing both the rings and grate bars. Also, the distortion tends to crack some rings, and when a failure of this nature occurs serious damage to the interior of the shredder or hammermill often ensues. It is theorized that the scrap metal lodges between the teeth on the rings as well as between the bars of the grate, and as the rings sweep along and subsequently away from the grate bars the lodged metal exerts distending forces on the rings which tend to elongate them.

One of the principal objects of the present invention is to provide a ring hammer for material reducing machines which will not elongate over sustained periods of operation. Another object is to provide a toothed ring hammer which efficiently shreds metal scrap. A further object is to provide a toothed ring hammer which is stronger than conventional toothed rings of present manufacture and less subject to failure. These and other objects and advantages will become apparent hereinafter.

The present invention is embodied in a ring-type hammer having outwardly projecting teeth which are interconnected by circumferentially extending fillets.

The invention also consists in the parts and in the arrangements and combinations of parts hereinafter described and claimed. In the accompanying drawings which form a part of the specification and wherein like numerals and letters refer to like parts wherever they occur:

FIG. 1 is a sectional view of a shredding machine provided with ring hammers constructed in accordance with and embodying the present invention;

FIG. 2 is an enlarged side elevational view of a ring hammer;

FIG. 3 is an end elevational view of a ring hammer; and

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2.

Referring now in detail to the drawings, 2 designates a shredding machine including a housing 4 having a rotor 6 journaled in it. The housing 4 is provided with an inlet opening 8 which opens downwardly toward the rotor 6 and upwardly into a hopper (not shown). One face of the opening 8 is defined by manganese steel liners 12 which extend downwardly and inwardly and terminate at a manganese steel grinding plate 14. Beyond the grinding plate 14 the housing is traversed by a plurality of spaced grate bars 16 arranged in an arc to form a grate 18 through which shredded material can pass.

The rotor 6 includes a rotor shaft 20 which extends transversely across the housing 4, and keyed to the rotor shaft 20 intermediate the sidewalls of the housing 4 are a plurality of abutting spiders 22 and a pair of end discs 24, the former being interposed between the latter. The spiders 22 are in turn provided with aligned but spaced radial arms 26, and fitted through the ends of each set of aligned arms is a ring restraining shaft 28. Intermediate the spaces between the arms 26 of adjacent spiders 22, each shaft 28 projects through a ring hammer 30. When the rotor revolves the ring hammers 30 by reason of the centrifugal forces generated assume outwardly projecting positions on the rotor 6. The circular paths described by the outermost portions on the hammers 30 pass in close proximity to the grinding plate 14 and the grinding bars 16, as well as across the inwardly presented end of the inlet opening 8.

As will be seen by reference to FIGS. 2-4, each ring hammer 30 possesses a generally circular body 31 provided with a cylindrical center bore 32 and parallel side faces 34 and 36 which are planar and perpendicular to the axis a of the bore 32. The diameter of the bore 32 is considerably larger than the diameter of the corresponding ring shafts 28, while the spacing between the side faces 34 and 36 is somewhat smaller than the axial distance between the opposed side faces on the aligned arms 26 of adjacent spiders 22. Consequently, each ring hammer 30 fits loosely between adjacent spiders 26 and is free to shift generally radially for a limited distance within the rotor 6, although axial shifting movement is practically negligible by reason of the close proximity of the spider arms 26 to the side faces 34 and 36.

Each ring hammer 30 integrally includes a plurality of circumferentially spaced teeth 38 which project outwardly and are bisected by equally spaced radii r emanating from the axial centerline a of the bore 32. The teeth 38 outwardly terminate at arcuate outer surfaces 40 which are radially equal so that they in effect define a cylinder, which is concentric with respect to the bore 32. Adjacent teeth 38 are separated from one another by reversely curved intermediate surfaces 42 and fillets or connecting segments 44, both of which are bisected by radii r located midway between the radii r,. The surfaces 42, in effect, are generated by radii r having their origins on the radii r slightly outwardly from the cylinder defined by the arcuate outer surfaces 40. The intersections of the surfaces 40 and 42 form cutting edges 43 on the teeth 38. The fillets 44, which are in effect integrally formed segments connecting the teeth 38, are located inwardly from the arcuate surfaces 40 and are generally trapezoidal or wedgelike in cross-sectional shape (FIG. 4), having outwardly converging planar side faces 46 and 48 which outwardly terminate at planar end faces 50 presented perpendicular to the radii r,,. The junctures cf the 4 end faces 50 and the pairs of converging side faces 46 and 48 form circumferentially extending cutting edges 51 on the fillets 44, and those cutting edges are located between the cutting edges 43 of the teeth 38. Moreover, the convergence of and the spacing between side of faces 46 and 48 of the fillets 44 are all such that the side faces 46 and 48 merge into the side faces 34 and 36, respectively, only at the radii r,. Accordingly, the reversely curved surfaces 42 intersect the side faces 34 and 36 at inwardly curved edges 52 which are substantially continuous between adjacent teeth 38.

The ring hammers 30 are preferably cast as an integral unit from an extremely hard and durable alloy such as manganese steel.

As previously noted the ring hammers are retained on the rotor 6 by means of the ring shafts 2% which extend axially through the center bores 32 of the hammers 30 as well as through the ends of the axially spaced arms 26 on the rotor 6. As the rotor revolves the hammers 30 swing outwardly by virtue of the centrifugal force generated and their arcuate outer surfaces 40 as well as their cutting edges 43 pass in close proximity to the grinding plate M and the grate bars 16 located within the housing 4.

When scrap metal consisting of stamping ends, tumings,

light castings, or the like, or for that matter, any other reducible material is introduced into the inlet opening 8 through the hopper it falls downwardly across liners l2 and into the path of the revolving ring hammers 30 which engage the scrap metal and draw it across the grinding plate 14 As the metal passes over the grinding plate M the edges 43 and 52 on the hammers 3t) tear into the metal and shred it to a smaller size. This shredding or tearing action continues as the metal is drawn across the grate bars 16, and when each piece of metal is small enough to pass intermediate the grate bars in it will fall downwardly where it is collected and then conveyed to a storage area or to a waiting rail car or other conveyance. That portion of the metal which is too large to pass through the grate 18 on the first pass is carried around by the rotor 6 and subjected to further shredding on subsequent passes over the grinding plate 14 and the grate bars 16 until it is small enough to pass through the grate 18. The impact of the teeth 38 on the hammers 30 against the scrap metal tends to turn the hammers 30 relative to the spiders 22 so that the teeth wear evenly. This in turn maintains the ring hammers 34) as well as the rotor 6 in acceptable balance even afterextended periods of operation. Upon encountering extremely tough or oversize pieces of metal the hammers 34B tend to fall back onto the rotor 6, or in other words, they give in the presence of such objects. Accordingly, the hammers 30 are not damaged or destroyed when they engage such objects.

The fillets 44 intermediate the teeth 38 prevent the scrap metal from lodging between the teeth 38 and this avoids any distending of the ring hammers 30 into an elongated configuration as the hammers 30 pass away from the grate 118. Accordingly, the bores 32 remain circular and the hammers 30 do not assume fixed positions on the rotor 6 as it revolves, nor do they distort to the extent that they engage and wear the grate bars 16. Thus, even after extended periods of operation the hammers 30 continue to rotate with respect to the spiders 26 upon impacting with the scrap metal infeed. Moreover, the fillets Ml rigidify the hammers 3th at their weakest points, that is between the teeth 38, and this further retards elongation. Also, the tendency to crack or otherwise fail at those points through fatigue or severe impacts is reduced considerably when compared to conventional toothed ring hammers. Nevertheless, the presence of the fillets does not detract from the effectiveness or the shredding ability of the hammers 30. Indeed, the same tooth geometry is maintained at the periphery of the hammer 30 as well as at the side faces 34 and 36 and the same number of cutting edges 43 and 52 are present on the hammer 30 as are available on conventional toothed ring hammers. What is more, the intersections of the side faces 46 and 48 and the end face 50 on each fillet 44 provide additional cutting edges 511 between the teeth 38 for cutting the metal. Consequently, the rotor 6 provided with ring hammers 3MB, shreds as efficiently.

While the ring hammers 343 are designed primarily for shredding scrap metal, they can, of course, be used on other material also.

This invention is intended to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.

lclaim:

l. A ring hammer for use in a material reducing machine which includes a housing, rotor journaled in the housing, and restraining means on the rotor outwardly from the axis of rotation thereof; said ring hammer comprising a generally circular body having a circular center bore positioned concentrically therein and receiving the restraining means so that the hammer is retained on the rotor, the bore having its axis generally parallel to the axis of rotation for the rotor and being substantially larger than the restraining means so that the hammer fits loosely on the restraining means and is free to rotate about its bore axis and relative to the rotor, teeth projecting outwardly from the body in a generally radial direction with respect to the bore axis, and connecting segments extending circumferentially between and interconnecting adjacent teeth, the connecting segments at their ends located furthest from the bore axis being axially narrower than the ends of the teeth located furthest from the bore axis.

2. A ring hammer according to claim 1 whereinthe connecting segments are set inwardly from the outer surfaces of the teeth.

3. A ring hammer according to claim ll wherein the teeth are separated by curved surfaces which curve inwardly toward the center bore and merge into the surfaces defining the connecting segments.

43. A ring hammer according to claim 3 and having parallel and planar side faces presented perpendicularly to the bore axis; and wherein the curved surfaces between the teeth intersect the side faces of the hammer at curved edges which are substantially continuous between adjacent teeth.

5. A ring hammer according to claim 4 wherein the teeth terminate at arcuate outer surfaces which are concentric about the bore and of equal radii.

6. In a material reducing machine which includes a housing, a rotor journaled in the housing and provided with restraining means outwardly from its axis. of rotation, and ring hammers encircling the restraining means and having outwardly projecting teeth; the improvement comprising curved surfaces separating the teeth of the ring hammers and generally circumferentially extending fillets connecting the teeth, the curved surfaces curving inwardly opposite to the general curvature of the hammers and the fillets having substantially planar end faces and side faces which converge outwardly toward the end faces, the curved surfaces merging into the side and end faces of the fillets.

7. The structure according to claim 6 wherein the end faces of the fillets are substantially perpendicular to radii located midway between adjacent teeth.

3. The structure according to claim 6 wherein the curved surfaces between the teeth intersect the side faces of the hammer at curved margins which are substantially continuous between adjacent teeth.

9. The structure according to claim 8 wherein the teeth terminate at arcuate outer surfaces which are concentric about the bore of the ring and are of equal radius whereby they define a cylinder, and wherein the curved margins are arcuate about points located at the radii midway between the teeth, the points being further located beyond the cylinder defined by the arcuate outer surfaces of the teeth.

10. A ring hammer according to claim ll wherein each connecting segment projects radially outwardly from the generally circular body and has side faces which converge outwardly.

111. A ring hammer according to claim 10 wherein the connecting segments outwardly terminate at end faces which intersect the converging side faces at circumferentially extending cutting edges.

112. A ring hammer according to claim 1 wherein each connecting segment is generally wedge-shaped in cross section with the narrowest portion of its wedge-shaped configuration being presented radially outwardly.

l3. For use in a material reducing machine, a rolling ring hammer having a circular center bore, the axis of which passes through the center of the hammer, the hammer further having radially outwardly projecting teeth and connecting segments extending generally circumferentially between the teeth, the outer ends of the connecting segments being positioned radially inwardly from the outer ends of the teeth and the axial segments project from the curved intermediate surfaces.

15. A ring hammer according to claim 13 wherein the teeth are provided with cutting edges beyond the ends of the connecting segments. 

1. A ring hammer for use in a material reducing machine which includes a housing, rotor journaled in the housing, and restraining means on the rotor outwardly from the axis of rotation thereof; said ring hammer comprising a generally circular body having a circular center bore positioned concentrically therein and receiving the restraining means so that the hammer is retained on the rotor, the bore having its axis generally parallel to the axis of rotation for the rotor and being substantially larger than the restraining means so that the hammer fits loosely on the restraining means and is free to rotate about its bore axis and relative to the rotor, teeth projecting outwardly from the body in a generally radial direction with respect to the bore axis, and connecting segments extending circumferentially between and interconnecting adjacent teeth, the connecting segments at their ends located furthest from the bore axis being axially narrower than the ends of the teeth located furthest from the bore axis.
 2. A ring hammer according to claim 1 wherein the connecting segments are set inwardly from the outer surfaces of the teeth.
 3. A ring hammer according to claim 1 wherein the teeth are separated by curved surfaces which curve inwardly toward the center bore and merge into the surfaces defining the connecting segments.
 4. A ring hammer according to claim 3 and having parallel and planar side faces presented perpendicularly to the bore axis; and wherein the curved surfaces between the teeth intersect the side faces of the hammer at curved edges which are substantially continuous between adjacent teeth.
 5. A ring hammer according to claim 4 wherein the teeth terminate at arcuate outer surfaces which are concentric about the bore and of equal radii.
 6. In a material reducing machine which includes a housing, a rotor journaled in the housing and provided with restraining means outwardly from its axis of rotation, and ring hammers encircling the restraining means and having outwardly projecting teeth; the improvement comprising curved surfaces separating the teeth of the ring hammers and generally circumferentially extending fillets connecting the teeth, the curved surfaces curving inwardly opposite to the general curvature of the hammers and the fillets having substantially planar end faces and side faces which converge outwardly toward the end faces, the curved surfaces merging into the side and end faces of the fillets.
 7. The structure according to claim 6 wherein the end faces of the fillets are substantialLy perpendicular to radii located midway between adjacent teeth.
 8. The structure according to claim 6 wherein the curved surfaces between the teeth intersect the side faces of the hammer at curved margins which are substantially continuous between adjacent teeth.
 9. The structure according to claim 8 wherein the teeth terminate at arcuate outer surfaces which are concentric about the bore of the ring and are of equal radius whereby they define a cylinder, and wherein the curved margins are arcuate about points located at the radii midway between the teeth, the points being further located beyond the cylinder defined by the arcuate outer surfaces of the teeth.
 10. A ring hammer according to claim 1 wherein each connecting segment projects radially outwardly from the generally circular body and has side faces which converge outwardly.
 11. A ring hammer according to claim 10 wherein the connecting segments outwardly terminate at end faces which intersect the converging side faces at circumferentially extending cutting edges.
 12. A ring hammer according to claim 1 wherein each connecting segment is generally wedge-shaped in cross section with the narrowest portion of its wedge-shaped configuration being presented radially outwardly.
 13. For use in a material reducing machine, a rolling ring hammer having a circular center bore, the axis of which passes through the center of the hammer, the hammer further having radially outwardly projecting teeth and connecting segments extending generally circumferentially between the teeth, the outer ends of the connecting segments being positioned radially inwardly from the outer ends of the teeth and the axial dimension of the hammer at the outer ends of the connecting segments being less than the axial dimension of the hammer at the outer ends of the teeth.
 14. A ring hammer according to claim 13 wherein adjacent teeth are separated by intermediate surfaces which are curved opposite to the general curvature of the ring; and wherein the segments project from the curved intermediate surfaces.
 15. A ring hammer according to claim 13 wherein the teeth are provided with cutting edges beyond the ends of the connecting segments. 